Grinding-mill.



PATBNTED PEB- 27, 1906.

P. T. LINDHARD. GRINDING MILL,

APPLICATION FILED JULY 1, 1904.

2 SHEETS-SHEET 1.

Ami

IIIIII/I/IIIIIIIIIIIIII PATENTED FEB. 27, 1906.

P. T. LINDHARD.

GRINDING MILL.

APPLICATION FILED JULY1,1904.

' z SHEETS-SHEET 2.

'IIIIl/I It'll ground or pulverized chine. tor separating sectional viewtaken] on the plane indicated by the line 2 2 in Fig. l and lookingtoward ri'rvrrnn g'lAglfES PATENT ornron.

reel 1, LINDHARD, or NEW YORK, n. r.

Specification of Letters Patent.

Patented Feb. 2?, recs.

Application filed July l, 1904. Serial No. 214,850.

To will wi'ww t it may conceive:

Be it known that l, PovL 'l. LrnnnAnn, a subject of the King of Denmark,end it resident of the borough of Manhetten, city of New York, State ofNew York, have invent- 7 ed certain new and useful Improvements inGrinding-Mills, of which the followin is a specification, referencebeing bad to t e occom psnying drawings, forming a pert hereof.

This invention relates to grinding-mills, and particularly to ballgrindingmills in which'the materiel to be ground is fed into a drum orother rotating member, where it is by the crushing action of the bellsprovided therein. In the reduction of 11' course material by such millsit is customary to. introduce the meteriel first into e mill havingrelatively large balls, where it is crushed up and round to a certainfineness, end then to feed the ground materiel into a, second mill, inwhich the bells are relatively smaller, where it is pulverized. Such a.method of reduction, as is clear, re-

uires the employment of two machines. such attempts esheve been madeheretofore to carry out this method of reduction by means of a singlemachine have, so far as is known, been unsatisfactory.

The object of this invention is to provide a mill compact inconstruction in which the crushing, grinding, screening, or sifting endthe lulverizingof the material can be accomplis red. at the some timeand in a single me.- For this purpose means are provided thefinely-ground material from the coarser particles or tailings afterthsfirst grinding and to return the tailings to the grindin or crushingdrum for further re duction and to'discherge the finely-ground materialto s second drum for pulverizing.

In the accompanying drawings, in which one embodiment of theinventionisillustreted for purposes of explanation, Figure 1 is e view invertical central section. Fig. 2 is 8.

Figs. 3 and 4 are respectively sectiozm views taken upon the planesindicated by tl ines 3 end i in Fig. 1 end looking l towcrd the l We 5is a detail cross-sew 1 tion taken on line 5 5 of Fig. l. in accordancewith the invention the mill l has three com mrtments-the drum o which Ireceives the materiel 'to be ground, the drum l), in which thefinely-ground material is pul- I separating-drum or sepethe right.

verized, and. the

into! 0, which receives the i'neteriel from the to the drum 1:, andreturns the teilings to the drum a.

together". in any suitab e manner, the separator being intermediate thedrums (1 and end the axes of the three drums being pref erebly in thesame line. Trunnions (i only be provided at either end of the apparatusto rest in journal-bearings e, and any suitable means (not shown) muy beprovided to rotote the drums in said bearings.

The construction of the drums a and b is immaterial to the presentinvention. The first drum 0,, receiving the material to be ground from ahopper f, which may be provided with a feeding device, such as ewormshaft 9, may have a relatively large diameter as compared-with thedrum 1), while the latter may be somewhat longer than drum a. Theinterior surfaces of the drums may be plain, as shown in Fig. 4, orcorrugated, as shown in Fig. 2, or stepped, as shown in Letters Patentof the United States 0. 69%,974, dated March 11, 1902, or otherwiseformed. Both drums are provided with bolls suitable for performing thework required, the balls in drum a being preferably larger and heavierfor grinding and crushing "hen the bulls in drum 5, which do thepulverizing.

The separating-drum or separator c is pro vided with screens 11., ofwhich any number may be employed. These screens extend from neer' thecenter of the drum to the circumference or periphery thereof and areprofersbly curved, as shown in the drawings, so that the material whichenters from the drum These three parts mey be secured a through openings71 may strike the concave side of the same and slide over the screens asthe separator rotates. it will be clear, however, tlmt, if desired, thescrews may be straight and substantially redial. that the screens may beeasily removable, they are preferably secured to the separator byforming grooves is in each of the. ends or heads Z of the separetingdrum c, in which grooves the screens are held. The openings l are madeof such a. size as to permit nmtoriel of a certain fineness only toenter the scperw tor, end these openin s are arranged in iron t of thescreens--tlmt is, so that the material. entering through the same willdrop upon the concave surfaces of the screens. The openings 'L arefurthermore located, preferably, near the circumference separator.Behind each screen is a purtiti on In order lOO TIC

m, which preferably conforms to the curvature of the screen and whichserves to receive the sifted matter from the screen and to keep suchsifted matter from becoming mixed with the fresh material entering theseparator.

from the drum a. These partitions also prefcrably serve to unitethe twoends or heads l of the separator, while the circumference of theseparator is closed by a" removable circular band a, the ends of whichare secured together by bolts 0. When the bolts are removed, the band isdetached from the separator, and the screens may be withdrawn and theinterior of the separator easily gotten at and cleaned.

Near the center of the separator means of communication are providedbetween the drum a and the forward side of e' ch screen" that is, theside upon which the material is received from drum a and between thedrum 1) and the other side of'each screen-that is,

the side where the finely-ground or sifted ma terial is delivered as itpasses the.screen--. whereby as the mill rotates the tailings are.returned to drum a and the finely-grounder sifted material is dischargedin drum b. For this purpose inclined plates g are provided, and theseplates are arranged between-the screens h and the partitions m, theplates in front of the screens being inclined so as to discharge intothe drum a, while the plates behind the screens are inclined so as todischarge into the drum '1). In the construction shown in the drawingsthere are four screens tions were continued into the center the lower orinner end. of each'lnchncd plate would form substantially an. angle oftortvfive degrees and. that the discliarge would take place through a 'lunni el-like passage formed by a screen, a plate, :tnd a partition andhaving a relatively narrow dischargc-' .openingwhcreby it would bepossible For the tailings or lines, as the case might be, to choke upsuch passage and opening. While such a construction is within thepurview of this inventiol'i, the screens are preferably not continued tothe center of theseparator; but the separator is provided at its centerwith a cylindrical structure whose periphery is indicatcd atr andthrough .which periphery the plates (1 extend. That portion of theperiphery in front of each plate, however, is removed, so as to permitthe free passage of the .material down the slide. lnthis way the slidesdischarging into drum 1) are broadened out after they pass the periphery7' oi the centhe discharge quadrants unobstructed. e ther drum is tocontain a large number of tral cylindrical structure, and the lower orinner ends of these plates form angles of ninety degrees with'each otherand are bounded on each side by partitions m, Figs. 2 and 3. One end ofthe central cylindrical structure has thus tour discharge-quadrants t,aswill be seen particularly from Figs. 2 and The other end of thecentral cylindrical structure is similarly provided with fourdischarge-quadrants 8, formed by .partitions p, extending from the innerends of the screens to the center of the separator and between which thelower ends of the plates discharging into drum (1 are received, thelower or inner ends of these plates being thus formed similar with thecorresponding ends of the plates discharging into drum 1). 'Moreover, itwill be clear from the drawings that within the central cylindricalstructure the partitions m are cut away. on one side from in front ofthe plates and that the partitions p are similarly cut away upon theother side, so as to leave It balls, as the drum b is-shown in thepresent case, a circular plate a may besecured in front of thedischarge-openings from the separator, leavim a narrow space betweensaid plate and the read through which the finelyground material maypassinto the chamber among the balls, but preventing the balls fromentering the separator. It will be obvious, of course, that a similarplate may be placed in front oi" the openings at the other end of the searator, although the same is not shown in thedrawings. I p

i In the operation of the mill the material to be ground is )laced inthe hopper f, from which it is Fed into the drum (1, where it is crushedand ground and from which it onters a separator through the openings iin front of the screens h, (the mill being rotated in the direction ofthe arrow, Fig. 3 Such material as enters the separator slides over thescreens as the mill rotates, and the sifted material drops upon thepartitions m beneath the screens and is discharged through the openings8 into th drum b. The tailings which do not pass the screens arereturned to the drum (1 through the ownings t. The linely-groumlmaterial enteril pulverized therein and discharged into a dust; casing11, comi'nunicating with an elevator, conveyer, or some other suitabledevice (not shown) for removing the material from the mill. The tailingsreturned to the drum c are commingled with the fresh material enteringfrom the hop er and are aga'in'subjected to the action 0 the balls insaid drum.

It will be understood that the mill is capable of many modifications andthat the invention is not limited to the precis form shown anddescribed.

I claim as my 1nV611t1011-- 1. in a grimling-mill, the combination of'ag the drum 1) is material from said drum and provided with the other ofthe drums.

' grinding-drum to receive the material to be ing inlet-openings meetinginto the comerases mind, a separator havin a com artment ormed thereinto receive t e part y-ground means Within the compartment for separatingfinely-ground material from the tailin s, and a second grindin -drum toreceive t e finelyound materia from the separator and pu verize thesame.

2. In a grinding-mill, the combination of a grinding-drum, means todeliver thereto material to be ground, a separator having acornpartmentformed therein, means to deliver the partly-ground material to theseparator, and a second grinding-drum, said separator havin means withinthe compartment adapted to deliver the finely-ground material to thesecond-named drum andalso having means within the com artment ada ted toreturn the tailings to t e first-namet drum.

3. In a grinding-mill, the combination of two grinding-drums, and anintermediate separator having a compartment formed therein, saidseparator having screens and partitions within its compartment and havpartment, the separator being also rovided with discharge-openingson oneSl( e of the screens communicating with one of the drums, and havingdischarge-openings on the-other side of the screens communicating withthe other drum. 7

4. In a. grinding-mill, the combination of two grinding-drums, and anintermediate separating-drum, said separating-drum having therein aplurality of screens and having artitions behind each of said screens tocatch the sifted matter, the drum also having inlet-openings near itsperiphery and discharge-openings near its center, both said inlet anddischarge openings being on one side ol the screens ant conln'nmicatingwith one of the drums, the separating-drum also havingdischarge-openings upon the other side of the screens and communicatingwith is in a grinding-mill, the combination of twogrinding-drumsand anintcrmediatcseparating-drinn, said separating-drum having a plurality ofcurved screens, and havin inletopcnings near its periphery anddiscnargcopenings near its cenlcr, both said inlet and 1 dischargeopenings bcing upon the concave sides of said screens and communicatingwith l one of the drums, lho scparating-drum also l having a partitionupon the other side ol'cach ol' the screens upon which the sil'tcdmatter is received and having a rlischargo-opcning between each screenand tho corrcspmlding partition communicating with the other drum.

(5. in :1 ball grimling-machine, the combination ol a grinding-drun-rhaving relatively large and heavy balls, :1 second grindingdrum havingrclati\"cly small and light balls, I

ing drum also having discharge openings I upon the other side of" thescreens commune,

eating with the drum having the smaller balls. v

7. In a grinding-mill, the combination of two grinding-drums, and anintermediate separating-drum, said separating-drum having within it aplurality of screens and partitions extending from near its center toits periphery and having inlet openings on one side of the screenstoward or near the periphery communicating with one of the drums, andalso having two sets of dischargeopenings toward or near the center, oneset being on the same side of the screens and communicating with thesame drum as the inlet-openings and the other set being on the otherside of the screens and communicating with the other drum.

8. In a grinding-mill, the combination of two griruling-drums, and anintermediate separating--drum, said scparatinglrum having therein aplurality of screens and partitions extending 'lrom'near its center toits periphery and having inlet-(mcnings on one side of the screenstoward or near the periphcry cormuunicating with one oi the drums, andtwo setsioi inclined plates within the separating-drum, the plates inone set extending from the same side of the screens on which theinlet-openings rem one drum to the separating-drum are located, and theplates in the other set extending from the other side of the screens tothe other drunr i). in a grinding-mill, the col'nhination of twogrimling-drums, and an intermediate scparating-drum, saidseparating-drum having therein a plurality ol' screens extending fromnear its center to its )cri ihcr a )lurality of partitions extendinglrom the ends oi the screens to the center of the separatingl drnm, aplurality m' partitions extending from the center of the separating-drumto its periphery, the scparating-drum having inletopcnings on thel'orward side of the screens comnrunicating with one drum, and two setsof inclined plates, the plates in one set extending lrom the spacesbetween the forward sides oi the screens and the secondnamod partitionsto the same drum with a which the inlet-openings communicate, and

the other set extending from the spaces hetween the rear sides of thescreens and the and the other set of plates crossing the secmovable bandaround I end-named partitions which are cut 0 ll above the plates, and.a central cylindrical structure through which the plates extend.

10. In at SGPiLIZltiUg-(llllfll for ball grinding-mills and the like,the combination of the ends or heads of the drum, having groovesextending from near the center toward the periphery, screens in thegrooves, and a re (l'ruin. I

This specification signed and witnessed this 21st day of June, A. D.1904.

POVL T, LINDHARD.

In presence 0f-- ANTHONY N. JESBERA. LUCIUS E. VARNEY.

the periphery of the 0

